Spinodal decomposition induced brittleness of Zr-Ta containing medium-entropy alloys

Abstract

Spinodal decomposition, originating from the miscibility gap, plays an important role in the mechanical properties of alloys. In this work, the correlations between the development of spinodal substructure and mechanical properties are investigated by a comparative study on TiZrTa and TiZrHfTa medium-entropy alloys (MEAs). The results indicate that Hf addition in TiZrTa alloy can reduce the spinodal decomposition propensity. Besides, compared to the arc-melt process, the fast-cooling rate of the drop-cast process dramatically freezes the spinodal separation at this initial stage with a small misfit and inhibits the brittle ω phase formation, which in turn increases the compression plasticity of the TiZrHfTa alloys. In short, this work clarifies the spinodal decomposition induced brittleness of the Zr-Ta refractory MEAs and would contribute to the design and preparation of high-ductile refractory multicomponent alloys.